Suction device and dressing

ABSTRACT

Some embodiments are directed to a system 10 for the application of topical negative pressure therapy to a site 18 on the body of a mammal. Some embodiments of the system 10 comprise a piston 22 and cylinder 24 device 12 having a self-contained power source for the generation of a reduced pressure and for aspirating the site 18. Some embodiments of the system 10 comprise a dressing 14 sealably surrounding the site 18 that can be operably connected to the device 12 by a conduit means 16 to apply the reduced pressure to the site 18.

PRIORITY INFORMATION

This application claims priority benefit under 35 § 119(e) ofProvisional Application 60/989,723 filed Nov. 21, 2007 and titledSUCTION DEVICE AND DRESSING, which application is hereby incorporated byreference as if fully set forth herein.

BACKGROUND Field of the Invention

Some embodiments of the present application relate to treating a site ona body by applying reduced or negative pressure to the site.

Description of the Related Art

The treatment of open or chronic wounds that are too large tospontaneously close or otherwise fail to heal has long been atroublesome area of medical practice. Closure of an open wound requiresinward migration of surrounding epithelial and subcutaneous tissue. Somewounds, however, are sufficiently large or infected that they are unableto heal spontaneously. In such instances, a zone of stasis in whichlocalized edema restricts the flow of blood to the epithelial andsubcutaneous tissue forms near the surface of the wound. Withoutsufficient blood flow, the wound is unable to successfully fightbacterial infection and is accordingly unable to close spontaneously.

An initial stage of wound healing is characterized by the formation ofgranulation tissue which is a matrix of collagen, fibronectin, andhyaluronic acid carrying macrophages, fibroblasts, and neovasculaturethat forms the basis for subsequent epithelialization of the wound,Infection and poor vascularization hinder the formation of granulationtissue within wounded tissue, thereby inhibiting wound healing. Ittherefore becomes desirable to provide a technique for increasing bloodcirculation within wounded tissue to promote spontaneous healing and toreduce infection.

Another problem encountered during the treatment of wounds is theselection of an appropriate technique for wound closure during thehealing process. Sutures are often used to apply force to adjacentviable tissue in order to induce the edges of a wound to migratetogether and heal. However, sutures apply a closure force to only a verysmall percentage of the area surrounding a wound. When there isscarring, edema, or insufficient tissue, the tension produced by thesutures can become great causing excessive pressure to be exerted by thesutures upon the tissue adjacent to each suture. As a result, theadjacent tissue often becomes ischemic thereby rendering suturing oflarge wounds counterproductive. If the quantity or size of the suturesis increased to reduce the tension required of any single suture, thequantity of foreign material within the wound is concomitantly increasedand the wound is more apt to become infected. Additionally, the size ortype of a particular wound may prevent the use of sutures to promotewound closure. It therefore becomes desirable to provide an apparatusand method for closing a large wound that distributes a closure forceevenly about the periphery of the wound.

Wounds resulting from ischemia, or lack of blood flow, are also oftendifficult to heal since decreased blood flow to a wound may inhibitnormal immune reaction to fight infection. Patients that are bedriddenor otherwise non-ambulatory are susceptible to such ischemic wounds asdecubitus ulcers or pressure sores. Decubitus ulcers form as a result ofconstant compression of the skin surface and underlying tissue thusrestricting circulation. Since the patient is often unable to feel thewound or to move sufficiently to relieve the pressure, such wounds canbecome self-perpetuating. Although it is common to treat such woundswith flaps, the conditions that initially caused the wound may also workagainst successful flap attachment. Wheelchair-bound paraplegics, forexample, must still remain seated after treatment of pelvic pressuresores. It therefore becomes desirable to provide a treatment procedurefor ischemic wounds that can be conducted in situ upon an immobile orpartially mobile patient.

Other types of wounds in which ischemia leads to progressivedeterioration include partial thickness burns. A partial thickness burnis a burn in which the cell death due to thermal trauma does not extendbelow the deepest epidermal structures such as hair follicles, sweatglands, or sebaceous glands. The progression of partial thickness burnsto deeper burns is a major problem in burn therapy. The ability tocontrol or diminish the depth of burns greatly enhances the prognosisfor burn patients and decreases morbidity resulting from burns. Partialthickness burns are formed of a zone of coagulation, which encompassestissue killed by thermal injury, and a zone of stasis. The zone ofstasis is a layer of tissue immediately beneath the zone of coagulation,Cells within the zone of stasis are viable, but the blood flow is staticbecause of collapse of vascular structures due to localized edema.Unless blood flow is re-established within the zone of stasis soon afterinjury, the tissue within the zone of stasis also dies. The death oftissue within the zone of stasis is caused by lack of oxygen andnutrients, reperfusion injury (re-establishment of blood flow afterprolonged ischemia), and decreased migration of white blood cells to thezone resulting in bacterial proliferation. Again, it becomes desirableto provide a technique for treating burn wounds by enhancing bloodcirculation to the wounded tissue to inhibit burn penetration.

There exist apparatuses utilizing reduced pressure for treatment ofthese types of wounds. However, the existing apparatuses do not haveadequate means to provide access to the area of the wound beneath thecover or dressing without disturbing the seal (be it adhesive orotherwise) between the dressing and the healthy skin surrounding thewound. Additionally, use of the existing apparatuses is often limited tolocally available power sources, or such apparatuses otherwiseexperience limitations in terms of the amount of suction that can beprovided to the dressing in the absence of electrical power.

SUMMARY OF SOME EMBODIMENTS

Some embodiments set forth herein are directed to systems, methods andapparatuses for wound therapy. In particular, some embodiments disclosedherein relate to a system for the generation and application of reducedpressure (compared with ambient atmospheric pressure) to a site on ahuman or animal body and to a dressing (also referred to herein as acover) at a wound site, and some embodiments relate to a wound dressingsystem configured to allow a user or medical practitioner to easilyaccess a wound bed without disturbing a seal between the dressing andthe healthy skin surrounding the wound. However, it will be appreciatedthat the systems, methods and apparatuses disclosed herein may haveapplication to other fields. In certain preferred embodiments, thewounds being treated may include, but are not limited to, acute andchronic wounds, orthopedic trauma wounds, and post-Cesarean wounds, toname a few.

Some embodiments disclosed herein are directed to treating such woundsby a method for the application of topical negative pressure therapy toa site on the body of a mammal, the method comprising: providing adevice comprising a cylinder, a piston disposed in the cylinder, and apower source operably connected to the piston, the power source beingconfigured to exert a constant force on the piston; operably connectingthe device to a dressing at the site by an aspirant conduit means,wherein the dressing can sealably surround the site; and applying areduced pressure to the site. In some embodiments, the power source canbe a self-contained mechanical motive power source such as, but notlimited to, a resilient tension applying device. For example, withoutlimitation the mechanical motive power source can be a coiled ribbonspring. The reduced pressure applied to the site can be held constant bythe constant force exerted by the power source on the piston of thedevice. In some embodiments, the cylinder and piston can comprise asyringe type device, and the reduced pressure can be generated byactuating the piston of the device, Any of the configurations of themethod for the application of topical negative pressure therapy to asite on the body of a mammal described above can further compriseoperably connecting a mechanical pump (which can be a hand operatedpump) to the dressing to generate the reduced pressure.

Some embodiments disclosed herein are directed to treating such woundswith a system for the application of topical negative pressure therapyto a site on the body of a mammal, the system comprising: a piston andcylinder device having a self-contained power source for the generationof a reduced pressure and for aspirating the site; and a dressing at thesite operably connected to the device by an aspirant conduit or otherconduit means to apply the reduced pressure to the site; wherein thedressing can sealably surround the site. In some embodiments, the devicefor the generation of reduced pressure can be a self-containedmechanical motive power source such as, but not limited to, a resilienttension applying device or other device that can apply a constanttension force. Some arrangements of the motive power source can have acoiled ribbon spring.

In any of the previously described embodiments, exudate from the sitecan be received by the piston and cylinder device, and/or the system canfurther be provided with a separate receptacle for receiving waste.Further, the piston and cylinder device can be a syringe-type device,and the device for the generation of reduced pressure can be a hand-heldpump. Further, in any of the previously described embodiments, thedressing can comprise a first adherent base portion configured tosealably surround the site and a second detachable portion sealably andremovably connectable to the first base portion. The first base portionand the second detachable portion of the dressing can have mutuallyengageable connection features which can, but are not required to,comprise male and female engaging portions and/or magnetic pieces suchas magnetic tape or magnetic strips. Further, the second detachableportion can include an integral occlusive drape portion or membrane, andat least one of the first base portion, the second detachable portion,and the occlusive drape portion can be provided with a tubular spigotfor the attachment of at least one separate aspirant conduit portion.

In some embodiments, any of the embodiments of the dressing describedabove can have a separate occlusive drape portion. Further, in any ofthe embodiments disclosed herein, either the first base portion or thesecond detachable portion, or both portions, can have an aspirantconduit incorporated therein. In some embodiments, the aspirant conduitcan be incorporated with a separate occlusive drape portion. In any ofthe embodiments disclosed herein, the dressing or site can be providedwith a wound filler and/or an absorbent material to absorb at least aportion of exudate from the site. The absorbent material can comprise,without limitation, polyacrylate particles. In some embodiments, theabsorbent material can comprise carbomethoxycellulose.

Some embodiments disclosed herein are directed to a method of treating awound comprising: sealably surrounding a wound site with a dressinghaving an adherent first base portion, and sealably connecting a seconddetachable portion to the first base portion. In some embodiments, themethod can further comprise positioning an occlusive drape between thefirst and second base portions, while some embodiments of the seconddetachable portion can substantially completely cover the first baseportion. Any of the embodiments of the methods of treating a wounddescribed above can further comprise applying reduced pressure to thewound site.

In some embodiments, such wounds can be treated using an apparatus forthe application of topical negative pressure therapy to a site on theskin of the body of a mammal, the apparatus comprising: a dressingconfigured to sealingly surround the site, the dressing comprising: abase portion configured to be supported by the skin surrounding thesite, the base portion optionally comprising an aperture formed axiallytherethrough; a detachable portion removably supportable by the baseportion; and a flexible membrane removably supportable by the baseportion, the flexible membrane optionally being configured to at leastcover the aperture formed in the base portion; wherein each of the baseportion, the detachable portion, and the membrane are optionally formedfrom a substantially impermeably material; and the dressing can beconfigured to form an approximately hermetically sealed enclosure overthe site when the detachable portion and the flexible membrane aresupported by the base portion.

In some embodiments, the apparatus can further comprise a reducedpressure generation device (which can be, without limitation, a pistonand cylinder device such as a syringe) configured to provide reducedpressure to the dressing, wherein the apparatus can be configured suchthat the reduced pressure generation device is in fluid communicationwith the dressing. Additionally, the reduced pressure generation devicecan comprise a self-contained mechanical motive power source which canbe, without limitation, a rolled spring. In some embodiments, thereduced pressure generation device can comprise a hand-held pump.

In some embodiments, such wounds can be treated using an apparatus forproviding a source of reduced pressure to a cover, the apparatuscomprising a conduit in communication with the cover; a first suctiondevice configured to allow a user to reduce the pressure within theconduit, the first suction device being removably connectable to a valvemember in communication with the conduit; a second suction deviceconfigured to allow a user to maintain the reduced pressure within theconduit, the second suction device being removably connectable to thevalve member; and a power source configured to provide power to thesecond suction device.

In some embodiments, such wounds can be treated using a method for theapplication of topical negative pressure therapy to a site on the bodyof a mammal, the method comprising: operating a first source of negativeor reduced pressure so as to provide reduced pressure to the cover; anddisconnecting the first source of negative or reduced pressure from thecover without the loss of a substantial amount of reduced pressure inthe cover.

In some embodiments, such wounds can be treated using a method for theapplication of topical negative pressure therapy to a site on the bodyof a mammal, the method comprising: sealingly enclosing the site with acover so that ambient air is substantially prevented from entering aspace between the cover and the site; connecting a suction device to thecover through a conduit so that the suction device is in fluidcommunication with the cover; operating the suction device until adesired level of reduced pressure within the dressing is achieved;connecting a mechanical vacuum system to the conduit so that themechanical vacuum system is in fluid communication with the cover;providing a power source configured to provide power to the mechanicalvacuum system; and operating the mechanical vacuum system so as tomaintain a desired level of reduced pressure within the cover.

Some embodiments of the present disclosure are directed to a conduitinsertion device for passing a length of conduit through a dressing(which can be, without limitation, any of the dressings disclosedherein), the conduit insertion device having a trocar supported within alength of conduit or tubing. In some embodiments, the conduit insertiondevice can be used to pass the conduit through either the flexible sheetor the second detachable portion of any of the embodiments of thedressing disclosed herein after the dressing has been positioned overthe wound. Some arrangements of the conduit insertion device can beconfigured such that, after the conduit has been passed through theflexible sheet or the second detachable portion (if the flexible sheetis not use), a tabbed or flanged surface that can be formed on a portionof the conduit can be sealably adhered or otherwise attached to theoutside surface of the flexible sheet or second detachable portion tosecure the conduit thereto.

For example, in some embodiments, a trocar can be supported within thetubular length of conduit that can be inserted through the dressing suchthat the trocar protrudes past the distal end of the conduit. In thisconfiguration, the trocar can be used to create a puncture hole in theflexible sheet, the second detachable portion of the dressing, and/orthe base portion of the dressing to permit the tubing to passtherethrough. After the tubing has been passed therethrough, the conduitmember may be advanced to a distance that is sufficient to permit anannular tabbed or flanged surface sealingly surrounding the tubing to beattached to, adhered to, or otherwise joined with the outside surface ofthe dressing so that an approximately hermetic seal is formed betweenthe conduit member and the dressing, at which point the trocar may bewithdrawn.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects and advantages will now be describedin connection with certain embodiments, with reference to theaccompanying drawings. The illustrated embodiments, however, are merelyexamples and are not intended to be limiting. The following are briefdescriptions of the drawings.

FIG. 1A is a schematic representation of the side of an embodiment of atopical negative pressure therapy system.

FIG. 1B is a schematic representation of the end of an embodiment of aspring unit that can be used with the embodiments of the topicalnegative pressure therapy system illustrated in FIG. 1A.

FIG. 2 is a schematic representation of the side of another embodimentof a topical negative pressure therapy system,

FIG. 3A is an exploded sectional view through the center of anembodiment of a dressing that can be used in a topical negative pressuretherapy system.

FIG. 3B is a sectional view through the center of the embodiment of thedressing shown in FIG. 3A showing a portion of the embodiment of thedressing in an assembled state.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The following detailed description is now directed to certain specificembodiments of the disclosure. In this description, reference is made tothe drawings wherein like parts are designated with like numeralsthroughout the description and the drawings. It is to be noted that anyof the features, components, configurations, sizes, materials, or anyother details set forth in this disclosure with regard to particularembodiments are meant to also be combinable or substitutable with thecomponents, features, or other details of any other embodiment disclosedherein where such a combination or substitution of such components,features, or other details is suitable.

Preferred embodiments described herein relate to wound therapy. The term“wound” as used herein, in addition to having its broad ordinarymeaning, includes any body part of a patient that can be treated usingreduced pressure. Wounds include, but are not limited to, open wounds,pressure sores, ulcers and burns. Treatment of such wounds can beperformed using negative pressure wound therapy, wherein a reduced ornegative pressure can be applied to the wound to facilitate and promotehealing of the wound. Additional descriptions of devices, methods, andsystems that can be used for wound therapy (e.g., for aspiration,irrigation, and cleansing of wounds) can be found in internationalpatent application publication numbers WO 2004/037334 (titled “APPARATUSFOR ASPIRATING, IRRIGATING AND CLEANSING WOUNDS”), WO 2005/046760(titled “WOUND CLEANSING APPARATUS WITH HEAT”), and WO 2005/105180(titled “APPARATUS FOR ASPIRATING, IRRIGATING AND/OR CLEANSING WOUNDS”),the entirety of each of which is hereby incorporated by reference as iffully set forth herein. It will also be appreciated that the negativepressure systems and methods as described herein can be applied to otherparts of the body, and are not necessarily limited to treatment ofwounds.

The apparatus and methods disclosed herein involve covering of the woundsite with a dressing which can be configured to be sealed to the skinsurrounding the wound by a flexible membrane type material through whichor sealed thereto are conduits or tubes that can carry fluids to thewound site and/or away from the wound site. The fluids can be liquidssuch as wound exudates and/or irrigation or cleansing fluids such assaline, for example, but can also be gases such as air, for example,used to aerate the wound site and to assist the liquid fluids away fromthe wound site by aspiration means.

The above-referenced patent application publications WO 2004/037334, WO2005/046760, and WO 2005/105180 describe systems for treating wounds bytherapy usually involving a plurality of conduits needing to be sealedin respect of the dressing/wound site in order to prevent ingress ofambient atmosphere into the wound site and to enable the apparatus towork effectively and efficiently without significant leakage. Otherembodiments of apparatuses are disclosed herein which apply topicalnegative pressure therapy to a wound having only one conduit or tubepassing into the wound site.

As mentioned, there is a need for simple and inexpensive topicalnegative pressure therapy systems in, for example, third world countriesand also for use by patients who wish to be mobile to continue daytimeoccupations while continuing beneficial topical negative pressuretherapy. In some embodiments, a device can be provided that mitigatessome of the disadvantages of known systems of reduced pressuregeneration.

Thus, according to some embodiments of the present disclosure, there isprovided a system for the application of topical negative pressuretherapy to a site on the body of a mammal (which can be a wound orotherwise), the system comprising a piston and cylinder device having aself-contained power source for the generation of a reduced pressure andfor aspirating the site. In some embodiments, a dressing can be providedtherewith, the dressing configured to cover the site and configured tobe connectable to the piston and cylinder device by an aspirant conduitmeans, such as but not limited to an aspirant conduit or tube. In thisarrangement, reduced pressure can be supplied to the dressing and,hence, the site. The dressing can be configured to sealingly surroundthe site.

In some embodiments, the device for generating a reduced pressure can bea syringe-type device having a cylinder and a slideable piston therein.The device can be configured to operate without a source of A/C power.In some embodiments, so as to be useable by a patient outside ofconventional medical facilities such as a hospital or a convalescentbed, for example, the device can have its own power source. The powersource can be a conventional battery, for example, powering aconventional DC electric motor driven pump. But, even theseconfigurations can be heavier than desired, and the need to replace orrecharge the batteries can be a disadvantage in terms of financial andinfrastructural resources. Again, such systems can be relatively costlyand also relatively inconvenient in terms of portability and continuedpower supply.

In some embodiments of the topical negative pressure generating device,the power source can be a mechanically generated motive source driving asimple suction generating unit such as a syringe-type unit, for example.Syringes are commonly available virtually everywhere in the world andare cheap and disposable. Syringes generally comprise a cylinder and anaxially slideable piston and are available in a wide range of differentsizes. The motive power for moving the piston in the cylinder in oneembodiment according to the present disclosure can be a self-containedresilient member such as spring unit, for example. Suitable spring unitsinclude, but are not limited to, coiled ribbon springs which areavailable in many sizes to apply a wide range of forces. Such springunits can effectively apply a constant tension to the piston/piston rodof a syringe. Such a power source can be configured to be lightweight,inexpensive, compact, and portable. The simplicity of the device meansit can be operated easily by any patient or clinician with a minimum oftraining.

Some embodiments of the device can also be provided with suitablefeatures related to pressure measuring means, such as, but not limitedto, mechanical or electronic sensors configured to display or reveal thepressure within the dressing and/or syringe cylinder, Some otherexamples of suitable pressure measuring devices which can be employedinclude, without limitation, purely pneumatic gauges or electronicgauges such as digital units, perhaps having their own battery powersupply.

Some embodiments of the device can also be provided with suitable valvearrangements to ensure that fluid flows are in the correct directions(i.e., so as to prevent air or fluid flow into the dressing) whengenerating a reduced pressure, and suitable valve arrangements to ensurethat reduced pressures are maintained in the dressing. In someembodiments, the valve can be configured such that one or more suctiondevices (such as, without limitation, a hand pump, suction bulb, amotorized pump, a battery powered pump, a piston and syringe device, orany other suitable suction devices) can be connected and/or disconnectedfrom the valve without the loss of pressure in the dressing.

Although wound exudates can be received directly into the pressurereducing syringe device and expelled therefrom when full into a suitablereceptacle or waste disposal system in the case of relatively smallwounds, a wound exudate fluid waste collecting receptacle to receive theaspirated exudate fluid from a wound site can be provided as part of theapparatus system in the case of larger wounds, for example. Suitablesupport means to support and accommodate the various features of thesystem devices can also be provided.

Additionally, in some embodiments, the system can comprise a manuallyoperated suction device for evacuation of a wound/incision to applytopical negative pressure to the wound and can be used with any dressingdesign known in the art of topical negative pressure. The device candiffer from other spring activated (kinetic devices) in that it can beconfigured to provide a substantially constant level of pressurethroughout the travel range of the piston in the cylinder. This is incontrast to known systems where a significant fall-off in pressure canbe measured along the length of travel of a piston or bellows system orin the case of pre-evacuated accumulator bottles or manualpump/reservoir systems where the pressure constantly diminishes as thesystem or reservoir fills with fluid. Where a syringe-type pressurereducing device is used, the reduced pressure delivered can becontrolled by choosing a different size of the syringe. For example,without limitation, the reduced pressure delivered can be controlled byvarying the diameter of the syringe cylinder that is appropriate to thetype of wound and wound volume. Additionally, without limitation, thereduced pressure delivered can be controlled by varying the size ofand/or number of springs used to provide the force on the syringe.

In the system according to certain embodiments, the pressure or rate ofpressure change generated can simply be controlled by using anappropriately sized syringe, i.e. by choosing a syringe with a differentsized diameter, or changing the size/force of the spring unit.

In some embodiments, one spring can be used. In some embodiments, two ormore springs can be used. Some embodiments of the device can be adaptedso as to receive and support any number of interchangeable springs arange of tensions.

References in this disclosure to pressure “fall-oft” or “diminishing”refer to the pressure difference between ambient atmospheric pressureand the reduced pressure pertaining in the dressing at the wound site.Therefore a reference to the pressure “diminishing” or “falling off” orother similar terms is meant to refer to the circumstance where thevacuum in the dressing is actually decaying and the pressure is risingtowards that of ambient atmospheric pressure.

In a modification of the device, the syringe device and spring pistonwithdrawal unit can be arranged to be disconnectable from the system andreplaceable by a hand-held pump to quickly reduce the pressure to adesired level. The connection between the pump/syringe motive source canbe a one-way valve such as a non-return check valve, for example. Thus,the syringe unit can be removed, the hand pump attached, the systemquickly pumped down, the hand pump removed and the syringe unitre-attached so as to maintain the desired reduced pressure. In someembodiments, a hand pump can be a bellows type hand pump, a suction bulbtype pump, or any other suitable pump, and can have some or all of thecharacteristics of the embodiments of any of the pumps described herein.

In some embodiments, the hand pump and the syringe system can besupported by the apparatus and arranged in parallel such that the handpump and the syringe system can be operated individually orsimultaneously. In this arrangement, for example, the hand pump can beused to provide an initial drawdown of pressure in the dressing,Additionally, during operation, the pressure provided by the syringe canbe augmented by operating the hand pump.

Additionally, in some embodiments, multiple syringe and piston units canbe supported by the apparatus and arranged in parallel (either with orwithout the hand pump described herein) so that each of the multiplesyringe and piston units can individually or simultaneously providereduced pressure to the dressing. For example, in some embodiments, theapparatus or system can be configured such that two or more syringe andpiston devices are arranged in parallel such that all of the piston andsyringe devices can be in fluid communication with the dressing,depending on the valve arrangement or settings. In this configuration,each of the syringe and piston devices can be individually attached toone or more springs so that, as one syringe and piston device becomesfilled with exudate or has otherwise reached its capacity, another ofthe syringe and piston devices can be activated, so as to continue toprovide reduced pressure to the wound dressing. If increased pressuredrawdown to the dressing is desired, more than one of the syringedevices can be spring activated.

Additionally, the apparatus can have a valve or valve system thatpermits any configuration or combination of the syringe devices or thehand pump device to be placed in fluid communication with the dressing.For example, in some embodiments having just a hand pump and a singlesyringe device, the valve can be configured to allow either the handpump or the syringe device to individually be in fluid communicationwith the dressing, or to allow both the hand pump and the syringe deviceto be simultaneously in fluid communication with the dressing.

In particular, FIG. 1A is a schematic representation of the side of anembodiment of a topical negative pressure therapy system 10. FIG. 1B isa schematic representation of the end of an embodiment of a spring unit26 that can be used with the embodiments of the topical negativepressure therapy system 10 illustrated in FIG. 1A.

The system 10 can comprise a device 12 for generating a reduced pressureoperably connected to a dressing 14 via a conduit 16. The dressing canhave any of the features or components of any of the dressings disclosedherein, or of any of the dressings known in the art or suitable for theapplication of reduced pressure. As illustrated, the dressing 14 isapplied to a wound site 18. The device 12 can include a syringe 20having a slideable piston/piston rod 22 moving in a stationary cylinder24, the piston/piston rod 22 being connected to the constant tensionspring units 26 each having a coiled ribbon spring 28.

In the illustrated embodiment, a spring unit 26 can comprise two or moreindividual constant tension spring units 26, two being shown. As thepiston 22 is withdrawn from the cylinder 24 by the spring units 26, avolume 30 in the syringe 20 is increased. A tubular spigot 32 on the endof the cylinder 24 can be connected to a four-way union 34 via a vacuumcheck valve 36 which can allow fluid flow in only the left to rightdirection as viewed in FIG. 1A. A second port of the 4-way union 34 canbe connected to a waste fluid reservoir 40 configured to receive wasteexudate from the wound site 18 via the flexible plastics materialconduit 16 operably connected at one end to the dressing 14 and at theother end to a third port in the 4-way union 34. A vacuum pressure gauge42 can be connected to the fourth port of the 4-way union. The spring,unit 26, syringe cylinder 24 and waste reservoir 40 can all be firmlyheld by a base plate 44 such that they are held substantially immobilerelative to each other. The end of the piston/piston rod 22 can beconnected to the ends of the ribbon springs 28 by a quickconnect/disconnect clip 46.

In use, the spring unit 26 can be initially disconnected from thepiston/piston rod 22 and the piston 22 traversed several times in thecylinder 24 so as to quickly reduce the pressure in the dressing 14,wound site 18, and/or the waste reservoir 40 to a desired level whichcan be confirmed by the gauge 42. In order to perform this initialevacuation of the dressing 14 and wound site 18, a manually orautomatically openable and closable exhaust valve 33 can be positionedbetween the syringe tubular spigot 32 and one-way valve 36 so that thesyringe 20 does not need to be disconnected to expel air at everystroke. Such a valve 33 can be a non-return valve configured to ventfluid to the atmosphere on a forward stroke to minimize volume in thecylinder 24. The piston/piston rod 22 can then be reconnected to thespring unit 26 by the clip 46, while the ribbon springs 28 are withdrawnfrom the spring unit 26 and the piston 22 is at the extreme left-handend of its travel, i.e. the syringe 20 is emptied. A constant springforce can then be automatically applied to the piston/piston rod 22 bythe spring unit 26 to withdraw it slowly in the rightwards direction. Asexudate fluid is removed from the wound and/or leakage of air occursinto the system, the piston 22 can move slowly rightwards (when orientedas in FIG. 1A), maintaining the reduced pressure in the system. Thereduced constant pressure is a function of the spring force and the areaof the piston/cylinder of the syringe unit 20. As fluid is drawn fromthe wound site 18 through the conduit 16, the fluid can reach the 4-wayunion and can be drawn into the waste reservoir 40. As mentioned above,multiple syringe systems devices 12 and multiple spring systems 26 canbe supported by the apparatus and used in fluid communication with thedressing 14.

FIG. 2 is a schematic representation of the side of another embodimentof a topical negative pressure therapy system. The system illustrated inFIG. 2 is a modified version of the system shown in FIG. 1 and isintended for quickly creating a reduced pressure at the wound/dressing18, 14. In this embodiment, a hand operated pump 50 is provided, someembodiments of which can have an integral pressure gauge 52. Although ahand operated pump is illustrated in FIG. 2 , other pumps can be used aswell, such as portable pumps including bulb pumps and portable batterypowered pumps.

The pump 50 can be initially connected to a non-return one-way flowcheck valve 54 by means of a tapered threaded adapter 56 being a part ofa connecting flexible conduit 58 between the pump 50 and check valve 54.The pump 50 can be configured to quickly reduce the pressure at thewound/dressing 18, 14 to a desired level. Once the desired pressurelevel is achieved, the pump 50 and conduit 58 can be disconnected fromthe valve 54, which can prevent or inhibit ingress of air into thedressing due to the valve 54 being a one-way valve. A pumping unit basedupon the syringe 20 and constant tension spring unit 26 constructiondepicted in FIG. 1 can then be connected to the check valve 54 so thatthe desired pressure level can be automatically maintained. The pumpingunit can also comprise a support to hold the cylinder 24 and spring unit26 in fixed relationship and furthermore can be connected to the checkvalve 54 by a similar flexible conduit (not shown) to the flexibleconduit 58 of the hand pump 50.

In some embodiments, the waste reservoir 40 can be similar or differentas compared to the waste reservoir 40 described above and illustrated inFIG. 1 in that the waste reservoir 40 illustrated in FIG. 2 can have aninlet port 60 connected to the conduit 16 to allow waste exudate fromthe wound to be captured in the waste reservoir 40 and an outlet port 62connected to either the hand pump 50 and/or to the aspirating syringe20, depending on what configuration is used. The outlet port 62 can beprovided with a suitable filter (not shown) such as a pathogen filter ofsuitable pore size to prevent liquid exudate from passing out of theport 62 and also to prevent potentially bio-hazardous bacteria fromeventually passing into the atmosphere.

In a further modification of the system of FIG. 2 , an electronicpressure gauge 70 can be provided, which can have its own battery powersupply. Some embodiments of the apparatus shown in FIG. 2 can also beoptionally fitted with an audible alarm to warn the user if the pressurehas deteriorated too far from a set point and the spring needsre-energizing.

A problem with conventional types of dressing is that they generallyadhere to the patient's skin in order to form a seal therewith so as toform a sealed site to which topical negative pressure therapy can beapplied. Generally, such dressings may need changing every day and insome cases much more frequently. In order to inspect a wound site forprogress in healing, conventional dressings generally need to be removedand then a fresh dressing applied. Due to the adhesive nature of thedressing drapes commonly used, this can cause additional trauma to thepatient by frequent removal of the dressing for whatever reason.Embodiments of the present disclosure are intended to mitigate some ofthe disadvantages of known systems of reduced pressure dressings.

In some embodiments, the dressing can comprise materials, aspects, andconfigurations of other topical negative pressure dressings known in theart, arranged or modified as described herein. Some embodiments of thedressings disclosed herein can comprise a thin, flexible sheet ormembrane (also referred to herein as an overlay portion) to cover thewound, as is described in greater detail below. Some arrangements of thedressing can have an aspiration conduit sealingly supported by theflexible sheet or membrane.

Some arrangements of the dressing can comprise at least two parts: afirst adherent base portion to sealably surround a wound site, forexample, and a second detachable portion sealably connectable andreconnectable to said first portion to seal site. The second detachableportion can be configured to completely cover and, hence, provide a sealwhen joined with the base portion: Alternatively, the detachable portioncan be configured to have an aperture formed therein so as to notprovide a complete seal when joined with the base portion. In thisarrangement, as will be described in greater detail below, a thin,flexible sheet can be provided that is positioned and sealinglysandwiched between the base portion and the second detachable portion. Abenefit of the separate flexible sheet is that the sheet can be changedat regular intervals or as necessary so that any bacteria that hascontaminated the flexible sheet can be discarded with the sheet and,hence, removed from the vicinity of the wound without requiring othercomponents of the dressing to be discarded.

Thus, in some arrangements, the base portion can be formed being agenerally ring-like shape having a circular or non-circular perimeter orshape. For example, without limitation, the base portion can have asquare, rectangular, circular, ovular, polygonal, or any other suitableshape. Additionally, the lower surface of the base portion can be planaror non-planner, depending on the contour or surface shape of the skin orother surface against which the base portion would be adhered or sealed.Because the base portion in some embodiments is configured to surroundthe wound, the base portion can be configured to define an aperturetherethrough that is sufficiently large so that the base portion onlycontacts the healthy skin surrounding a wound.

As mentioned, some embodiments of the second detachable part can have ageneral shape that is similar to the shape of the base portion so thatthe tube can be joined together without any mismatch therebetween.However, because the base portion and the detachable portion areconfigured to be sealingly joined, the geometry of the base portion andthe detachable portion pertaining to the sealing components can bedifferent. For example, in some embodiments, the base portion can definean annular protrusion or tongue, as it is commonly referred, while thedetachable portion can define an annular channel or groove configured toprovide a seal when joined with the annular protrusion or tongue of thebase portion. In this and other configurations, therefore, the second ordetachable portion of the dressing can be detached from the first orbase portion of the dressing so that the raised portion of the dressingcan remain in place, adhered to the patient's skin. Additionally, thedetachable portion and/or flexible sheet described above can bereplaceable so that, if either of these components are contaminated suchas by bacteria, they can be replaced with new, fresh components or canbe cleaned or otherwise decontaminated without disturbing the wound andalso without incurring the cost and time required to replace the baseportion, and without causing irritation to the patient's healthy skin.

Thus, it will be seen that the first on base portion can be configuredto remain in place around the wound, and tests have shown that it isfeasible for the first part of the dressing to remain in place for up toa week. Additionally, in the same arrangements, the second or detachableportion can be′ removed by a clinician for inspection of the wound,changing or replacing of the gauze, foam, or other wound packing meanswithin the dressing, cleansing of the wound, cleansing of the removableportions of the dressing, or for any other suitable purpose. Thedetachable portion can then be re-joined with the base portion withoutdisturbing the seal between the base portion and the skin surroundingthe wound. The detachable second portion need not have any adhesive onit which contacts the wound area per se.

As mentioned, the wound cavity can be provided with any suitable woundfilling material known in the art. In some applications, the woundfilling material can be configured to maintain the edges of the woundcavity apart from one another and to promote the growth of new materialfrom the wound bed so as to prevent the formation of closed cavities.The embodiments of the dressing disclosed herein facilitate the use ofwound filler materials by allowing any internal wound fillers, woundpacking materials, or waste absorbing materials to be easily accessed byremoving the second detachable portion of the dressing withoutdisturbing the seal between the lower base portion and the patient'sskin.

In arrangements where the dressing comprises a flexible sheet sandwichedbetween the base and the detachable portion of the dressing, theflexible sheet can provide the advantage of being able to collapse overand cover a wound filler that can be placed within the dressing. In someembodiments, the flexible sheet can be configured to cover a woundfiller that protrudes above the edge of the detachable portion of thedressing in a manner that may not be achievable with a more rigid wounddressing.

In some of the embodiments described herein, because the volume orcapacity of the exudate waste collecting receptacle can be limited orrelatively small, the gauze or wound packing material can be selected sothat the apparatuses described above can have additional means forcollecting waste fluid. Providing additional means for collecting wastefluid can extend the time periods between which the waste receptacleneeds to be emptied or replaced. This may be particularly useful inapplications where the topical negative pressure therapy system is usedas a portable system to allow patients to lead a relatively normal lifewhile continuing their therapy (though in theory the waste receptaclecould be as large as desired).

Thus, in some embodiments, the wound packing material may comprise aso-called “superabsorber” material to absorb excess waste fluids whichwould otherwise be aspirated to the waste receptacle. In someembodiments, between approximately 50% and approximately 100% of thefluids exuded by the wound can be absorbed by the superabsorber with theremaining portion of the fluids exuded by the wound can be aspirated tothe waste receptacle or otherwise, A suitable material for asuperabsorber can be polyacrylate (in particle form or otherwise),calcium alginate, and/or carboxymethycellulose.

In some embodiments, the superabsorber can be held within a porous orpermeable bag within the dressing, and can be positioned adjacent thewound. In some embodiments, the wound packing material can be acomposite containing the superabsorber material, such as gauze withsuperabsorber particles or fibers contained therein, or a foam materialsuch as ALLEVYN PLUS™ having polyacrylate superabsorber particlestherein. In some embodiments, the superabsorber material can bepositioned or layered on top of a porous foam material or other suitablematerial so that exudate travels through the foam or other materialbefore being absorbed by the superabsorber material. This arrangementwould allow a user or medical practitioner to easily and quickly changethe superabsorber material with or without changing the other woundpacking materials.

Consequently, it will be seen that some embodiments of the dressingsystem disclosed herein can have at least two advantages. First, someembodiments of this dressing can result in reduced trauma to the patientsince the base part can remain in sealing contact on the patient formuch longer than with conventional topical negative pressure dressings.Additionally, the base portion can be configured so as to reduce thearea of contact with the patient's skin. Furthermore, the seconddetachable portion need have no adhesive which contacts either soundskin or the wound itself, again leading to reduced trauma for thepatient.

In the case where the wound site comprises a skin graft or skinreplacement product, for example, which often are secured with minimalsuture material, topical negative pressure can be used to apply amoderate pressure via a positive pressure from the ambient atmosphere tothe graft to stabilise the graft and assist with complete contact overthe graft area. The use of topical negative pressure in skin graftsurgery also helps to prevent the graft from being continuously wet byremoving any excess fluids via the aspiration conduit. The fact that thesecond portion may have no adhesive thereon, in contrast to conventionalself-adhesive drape materials, can reduce the danger of possibly harminga delicate bond of the graft to the wound site.

The first base portion of the dressing may be provided with aconventional type of multi-layer construction to both protect adhesivecoated surfaces with a removable and discardable protector layer and asupport layer to assist handling of the dressing portion immediatelyprior to adhering to a patient. If provided with an adhesive layer, thesecond portion can also be provided with similar protective and supportlayers.

In some embodiments, however, the second or removable portion can beprovided with an adhesive layer to adhere the first and second portionsof the dressing together, There can be particular applications wherethis arrangement is preferred. Other arrangements of the dressing, asdescribed herein, can be configured such that the base portion and thedetachable portion are provided with mutually co-operating joining andsealing means.

Mutually cooperating sealing means may, in some embodiments of thepresent disclosure, comprise co-operating ring portions on the two partswhich have engaging male and female portions (in cross section) formedfrom a soft, conformable material such as but not limited to a siliconerubber type material, polyurethane, PE, PP, PVC, EVA, for example.Suitable materials can have a Shore A hardness in the range from about70 to about 100, hut this range is not limiting.

Therefore, in some arrangements of the dressing, the second portion canbe configured so that it forms a seal enclosure over the first baseportion. For example, a second portion can be configured such that aflexible drain or window portion (whether translucent, transparent, orotherwise) can be integral or otherwise adhered to the second portion.Alternatively, some arrangements of the dressing can be configured suchthat a separate drape or flexible film material (such as can be formedfrom, without limitation, a translucent, transparent, opaque plasticmaterial or any other suitable material) but which can be held in placeby being sandwiched between the male and female co-operating portions ofthe base and detachable portions. Although co-operating male and femaleformations or features are described above for joining the base portionand the second detachable portion, alternative joining means such asmagnetic material filled tapes, for example, can be used.

In particular, with reference to the accompanying figures, FIG. 3A is anexploded sectional view through the center of an embodiment of adressing that can be used in a topical negative pressure therapy system,and FIG. 38 is a sectional view through the center of the embodiment ofthe dressing shown in FIG. 3A, showing a portion of the embodiment ofthe dressing in an assembled state.

The embodiment of the dressing 80 illustrated in FIGS. 3A and 3B can beused in the system illustrated in FIGS. 1A, 1B, and/or 2. As mentioned,FIG. 3A shows the dressing 80 in exploded form showing the constituentparts situated above a schematic wound 82 surrounded by healthy skin 84,and FIG. 3B shows a detail of the first base portion 88, the seconddetachable portion 90, and the occlusive drape material or membrane 92joined together with the membrane 92 sandwiched between the first baseportion 88 and the second detachable portion 90. The dressing cancomprise a first base portion 88 and a second detachable portion 90. Inthis embodiment, the second detachable portion 90 can be in the form ofa ring member which can be removably attached to the base portion 88 byco-operating male and female engagement features described below. Insome embodiments, the membrane 92 can be a separate component formedfrom a thin, flexible material and can be provided between the firstbase portion 88 and second detachable portion 90. In some embodiments,as described above, the detachable portion 90 can be configured tocompletely cover the base portion 88 and hence, the wound 82. In someembodiments, the membrane 92 can be integrally formed with thedetachable portion 90, or can be separately formed and adhered orotherwise fixed to the detachable portion.

In some embodiments, the detachable portion 90 can be hingedly connectedor otherwise tethered to the base portion 88. In some embodiments, thedetachable portion 90 can be untethered from the base portion 88, sothat the detachable portion 90 can be completely removed from the baseportion H.

Prior to attachment to the skin 84, the first base portion 88 cancomprise a flexible plastic material backing layer 94 having a layer ofpressure sensitive adhesive 96 coated on the surface 98 which isconfigured to contact the skin in use. The adhesive layer 96 can beinitially protected by a plastic material protective layer 100 which canbe peeled away prior to adhering to the patient. Depending upon the sizeand physical stiffness of the carrier layer 94, a further removableadhesive stiffening carrier layer (shown as dashed lines 104 in FIG. 3 )can optionally be provided upon the upper surface 102 of the backinglayer 94 to aid handling of the first base portion 88 after removal ofthe adhesive protection layer 100. The carrier layer 104 can be peeledaway after attachment of the first base portion 88 to the patient. Thefirst base portion 88 can also be provided with a connector ring 106adhered thereto. The first base portion 88 and any other suitablecomponent of the dressing 80 can be formed from a soft conformablematerial such as, but not limited to, a plastic or rubber material suchas a silicone rubber or other materials as described hereinabove. Theconnector ring 106 can have a foot portion 108 for greater bondingstrength and stability and an upstanding male engaging portion 110molded therewith.

The second detachable portion 90 can be a ring member of correspondingsize to that of connector ring member 106 and can be provided with afemale engaging portion 112 to cooperate with and receive the maleportion 110 of the connecting ring 106 therein. In some embodiments, theinterconnection of the male and female engaging portions 110, 112 cancreate an airtight or approximately airtight seal. The second ringmember 90 and any other suitable component of the dressing 80 can beinoided from a soft conformable plastic material such that forces tojoin the first base portion 88 and the second detachable portion 90 arerelatively low, so as to avoid trauma to the patient. Any components ofthe dressing 80 can be sized and shaped, so as to accommodate a widerange of wound sizes and body surface contours.

Some embodiments of the dressing can comprise an aspirant conduitconfigured to allow a source of reduced pressure to be applied to thevolume beneath the dressing. In some embodiments, the aspirant conduitcan be incorporated into the dressing by providing separate, occlusivedrape portions having one or more aspirant tubes sealed thereto readyfor installation in a dressing. The drape portion can be configured tobe removably sandwiched between the base portion and the detachableportion, or can be configured to be integrally formed with or otherwisefixed to the second detachable portion of the dressing. This can beadvantageous where a separate occlusive drape portion can be employedhaving no adhesive coating layer.

Some embodiments of the aspirant coolant can comprise a valve orconnector configured to receive and mate with a length of tubing from,for example, the source or reduced pressure. The aspirant conduit meanscan be formed as an integral part of the first base dressing portionduring manufacture having a flexible, overlong conduit which can be cutto a desired length, both internally and externally of the dressingsite, during application of the dressing to the wound site.

Alternatively, in some embodiments, the base first portion can have atubular spigot molded or otherwise incorporated therewith and to whichan aspirant conduit can be connected. Such a spigot can have a portionof the aspirant conduit connected internally of the dressing and canhave an additional portion of aspirant tube to connect to aspiratingpump means after placement of the dressing on a patient.

With reference to FIGS. 3A and 3B, an aspirant conduit 120 can beincorporated in several ways into the dressing 80. In addition to theways described above, as shown in FIG. 3A, a conduit 120 can be passedthrough the drape 92 and sealed thereto at points of contact 122. Thiscan be achieved by providing occlusive drape portions having aspiranttubes sealed thereto and configured to be ready for installation in adressing as described. Additionally, the base portion 88 can have anaperture formed therein, the aperture being configured to receive andallow a conduit to pass therethrough. The aperture can be configured sothat, as the conduit is passed therethrough, a sufficient seal can beformed between the aperture and the conduit. In some embodiments, anadhesive or suitable sealing material can be applied to seal the outsidesurface of the conduit with the aperture.

Generally, conduits or tubes passing into the wound site in any of theembodiments described herein can be sealed to a flexible wound coveringmembrane or film by “pinching” the flexible covering around the conduitor tube so as to both stick the membrane material to the conduit or tubeand also to itself to itself to form a seal with the tube Generally, thetypes of flexible membrane material used for wound coverings areprovided with an adhesive layer such as a pressure sensitive adhesive,for example, in order for the material to adhere to the skin surroundinga wound.

In some embodiments, a conduit insertion device having a trocarsupported therein can be used to pass the conduit through either theflexible sheet or the second detachable portion after the dressing hasbeen positioned over the wound. Some arrangements of the conduitinsertion device can be configured such that, after the conduit has beenpassed through the flexible sheet or the second detachable portion (ifthe flexible sheet is not use), a tabbed or flanged surface that can beformed on a portion of the conduit can be sealably adhered or otherwiseattached to the outside surface of the flexible sheet or seconddetachable portion to secure the conduit thereto.

For example, in some embodiments, a trocar can be supported within thetubular length of conduit that can be inserted though the dressing suchthat the trocar protrudes past the distal end of the conduit (i.e., theend of the conduit to be positioned within the dressing). In thisconfiguration, the trocar can be used to create a puncture hole in theflexible sheet, the second detachable portion of the dressing, and/orthe base portion of the dressing to permit the tubing to passtherethrough, After the tubing has been passed therethrough, the conduitmember may be advanced to a distance that is sufficient to permit anannular tabbed or flanged surface sealingly surrounding the tubing to beattached to, adhered to, or otherwise joined with the outside surface ofthe dressing so that an approximately hermetic seal is formed betweenthe conduit member and the dressing. At that point, the trocar may bewithdrawn and the proximal end of the tubing (i.e., the end of thetubing that is located outside of the dressing), may be connecteddirectly or indirectly to the supply of reduced pressure.

Throughout the description and claims of this specification, the words“have,” “comprise,” “contain,” and variations of the words, for example“comprising” and “comprises”, means “including but not limited to”, andis not intended to (and does not) exclude other moieties, additives,components, integers or steps.

Throughout the description and claims of this specification, thesingular encompasses the plural unless the context otherwise requires.In particular, where the indefinite article is used, the specificationis to be understood as contemplating plurality as well as singularity,unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties orgroups described in conjunction with a particular aspect, embodiment orexample of the invention are to be understood to be applicable to anyother aspect, embodiment or example described herein unless incompatibletherewith.

While the above detailed description has shown, described, and pointedout novel features as applied to various embodiments, it will beunderstood that various omissions, substitutions, and changes in theform and details of the device or process illustrated can be madewithout departing from the spirit of the disclosure. Additionally, thevarious features and processes described above can be used independentlyof one another, or can be combined in various ways. All possiblecombinations and subcombinations are intended to fall within the scopeof this disclosure.

As will be recognized, certain embodiments described herein can beembodied within a form that does not provide all of the features andbenefits set forth herein, as some features can be used or practicedseparately from others. The scope of the inventions is indicated by whatis claimed in this and/or future applications rather than by theforegoing description. All changes which come within the meaning andrange of equivalency of the claims in this and/or future applicationsare to be embraced within their scope.

1.-40. (canceled)
 41. An apparatus for application of topical negativepressure therapy, the apparatus comprising: a dressing configured tosealingly surround a wound site, the dressing comprising: a first baseportion comprising an aperture; and a second detachable portionconfigured to be removably connected to and entirely removable from thefirst base portion, wherein the first base portion and the seconddetachable portion comprise mutually engageable connection featuresconfigured to join the second detachable portion to the first baseportion so that the second detachable portion forms an enclosure overthe first base portion when the second detachable portion is removablyconnected to the first base portion; wherein the mutually engageableconnection features of the first base portion comprises a connectormember that surrounds the aperture; and an aspiration conduit configuredto apply negative pressure to a volume beneath the dressing.
 42. Theapparatus of claim 41, wherein the mutually engageable connectionfeatures comprise male and female engagement features.
 43. The apparatusof claim 41, wherein the mutually engageable connection featurescomprise magnetic pieces.
 44. The apparatus of claim 41, wherein themutually engageable connection features comprise tongue and grooveconnections.
 45. The apparatus of claim 41, wherein the seconddetachable portion comprises a ring member that is removably attachableto the first base portion.
 46. The apparatus of claim 41, wherein thesecond detachable portion is configured to completely cover the firstbase portion.
 47. The apparatus of claim 41, wherein the seconddetachable portion is hingedly connected to the first base portion. 48.The apparatus of claim 41, wherein the first base portion is attached toa flexible backing layer and further comprising an adhesive on a woundfacing surface of the hacking layer for adhering the dressing around thewound site.
 49. The apparatus of claim 41, further comprising anabsorbent material configured to absorb at least a portion of exudatefrom the wound site.
 50. The apparatus of claim 41, further comprising areduced pressure generation device configured to provide negativepressure through the aspiration conduit.
 51. An apparatus for theapplication of topical negative pressure therapy, the apparatuscomprising: a dressing configured to sealingly surround a wound site,the dressing comprising a cover layer configured to form a seal over thewound site, the cover layer comprising a first wound facing surface anda second surface opposite the first surface; a conduit configured toprovide fluid communication between the dressing and a source ofnegative pressure; and a piercing member configured to create a puncturehole in the cover layer to facilitate fluid communication between theconduit and the cover layer; wherein the conduit comprises a flangedsurface configured to adhere to the second surface of the cover layer atthe puncture hole in the cover layer and configured to form a sealbetween the conduit member and the dressing.
 52. The apparatus of claim51, wherein the piercing member comprises a trocar.
 53. The apparatus ofclaim 51, wherein the cover layer comprises an adhesive on the firstsurface of the cover layer for adhering the dressing around the woundsite.
 54. The apparatus of claim 51, wherein the dressing furthercomprises an absorbent material configured to absorb at least a portionof exudate from the wound site.
 55. The apparatus of claim 51, furthercomprising a source of negative pressure configured to provide negativepressure through the conduit.